1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) field, more particularly, to a light guiding system, an edge-lighting backlight module and an LCD device.
2. Description of the Prior Art
The popular backlight from a backlight module of a TFT-LCD device is light emitting diode (LED) or fluorescent tube. Both lighten by power, and the percentage of the energy consumption from the backlight in the whole backlight module is around 80 so that it consumes energy tremendously in the long term. Therefore, it results in the greenhouse effect and the nuclear pollution because of the main power generations, such as oil and coal burning and nuclear energy.
Ambient light in nature, like sunlight, is environmental and natural resource. The spectrum of the ambient light comprises visible light which backlight needs, and a design of a backlight module gathers sunlight by an ambient light gathering system and guides the light taken as backlight to the backlight module by a light guiding device, such as optical fiber. Therefore, it saves energy consumption enormously.
As FIG. 1 shows, FIG. 1 is a structure diagram of a light guiding system of an edge-lighting backlight module in the prior art. A light guiding system 1 absorbs ambient light CL and generates absorbed light SL by an ambient light gathering system 10. The absorbed light SL is guided into a plurality of optical fibers 20 whose a light output end 21 adjacent to a light-in side 31 of a light guide plate (light guide plate) 30, the light from each light output end 21 passes the light-in side 31 to the light guide plate 30, and then the light mixed evenly in the light guide plate 30 emits from a light-out side 33. In hence, the light from the light output end 21 is taken as a backlight of the backlight module 1.
The main problem that the structure of the conventional edge-lighting backlight module is optical uniformity on the light-in side 31 of the light guide plate 30 because a larger interval between two adjacent light output ends 21 in the arrangement of the plurality of optical fibers 20 adjacent to the light-in side 31 of the light guide plate 30 caused by a smaller light-out angle of the light output end 21 in the optical fiber 20 (within 60 degrees in general). Therefore, the optical uniformity deteriorates an optical quality. It needs more optical fibers 20 if an interval between two adjacent light output ends 21 reduces. If so, it increases costs and manufacturing difficulty.